Objective To observe pulsative index (PI), resistant index (RI) of placental helicine arteries by colour Doppler, analyses relation between PI, RI and developing of pregnant hypertension.

目的采用彩色多普勒检孕妇子宫胎床螺旋动脉搏动指数（PI），阻力指数（RI），预征的发生、发展及预后。